I drained the oil and it came out with the fine particles that are common in diffs but nothing too major, but a drain & fill was definitely warranted. I refilled with Royal Purple and 1200 miles later it was black. I hope that it was just cleaning.

Does anybody know if the PTU is a "Wet Clutch" type system?? Royal purple says 75w-140 product I used was correct for my application, but the bottle says "not for wet clutches". Either way, I'm gonna change it today with stupid expensive motorcraft synthetic 75w-140.
Here are some pics after less than 1200 miles.
http://www.bobistheoilguy.com/forums...2645634&page=1

I noticed a very slight leak coming from the vent tube where it connects to the box. I will fix that and plan to add a fuel filter to the end of the vent tube to help keep the oil clean. (we had filters on all our gear boxes when I worked in an industrial setting maintaining hydraulic units and large gear boxes)

Gonna add a hose to the rear diff vent plug as well with filter to move farther away from road debris. Current vent sets right on the cover near the road debris.

 

Ford's PTO/PTU (simple ring & pinion) has been proven to be a high stress point, "weak link", in their F/awd system using the rear clutch pak. Mazda added cooling to their's and the new Explorer also uses cooling.

You might want to consider extending the service life of the F/awd system components via adding an "off" switch in the rear electromagnetically actuated clutch circuit. Only turn it on for suspected or KNOWN adverse roadbed conditions.

Leak from the vent tube would normally indicate overheating, if not overfilled, of the lubricating fluid, not unusual for Ford.

 

Thank you for your response.

I have some clarifying questions,
1. The PTU/PTO is near center vehicle, just behind the eCVT?
2. The rear clutch pak is at the rear just in front of the rear differential?

Is the best way to put the switch in via relay, or is it low enough current that it can be put in-line?

Where would I tie in to, the wires going to the rear clutch pak (just in front of the rear diff?

Thanks,
Chris

 

p.s.

I flushed the RP oil out with wal-mart gear oil, (short 10 minute drives between each one) then put in Motorcraft synthetic gear oil.

I installed a filter on the end of the PTU vent hose and added a hose to the rear diff with a filter on it as well. Just used cheap fram clear fuel filters.

Over Memorial day weekend, I went on a trip and encountered severe 50mph headwinds. To maintain speed, the RPM's were 4k-5k most of the trip. I suspect any heating issues were during that trip.

 

He owns a Prius, not an Escape. Definitely get additional input from a trusted source before you act on any of those recommendations.

 

I started to wonder if we were talking about the same thing?

I thought ring and pinion are found in differentials, not transfer cases (at least in trucks) tho I wasn't sure if the PTU was something special tho.
PTO is power take off (used as an auxiliary output shaft to power accessories like winches, air compressors, etc. often from the transfer case.)

Thanks for the heads up. I always check my sources, and use the posts to steer my research.

 

Your FEH does not have a "transfer case" in the traditional use of the term. Tradtionally a transfer case involves a means to engage/disengage the "extra" driveline, most often the front driveline, and a means to transfer between hi/low gear ratios.

In your FEH the extra driveline engage/disengage functionality, "linear" functionality in this case, is accomplished via the clutch system housed within the front of the rear differential. You have NO hi/lo gear ratio capability.

So all that is needed is a method to convert the lateral drive output of the CVT into a longitudinal one, ring and pinion, or in this case maybe more correctly stated "pinion and ring".

Not owning an FEH, Escape or Mariner does not mean that I can't read and comprehend the Ford shop/repair manuals readily available online.

 

A good heavy duty DPST switch will do the job quite well. DP, Double Pole so that a power resistor equal to the rear clutch electromagnet coil resistance can be switched into the circuit in the "off" position to "fool" the F/awd ECU.

 

The "colour" change from purple to black may have well been meaningless. The purple dye may not well endure the heat level involved and may well turn "black" without the functionality of the base lubricating oil being compromised at all. That being said it be best to not take chances.

 

I have a better understanding, thanks.

I assume the rear drive shaft is being powered at all times through the PTU, but disengages/engages at the clutch housing at the rear of the vehicle, just in front of the rear diff.

How would disengaging the clutch electro-magnet (via switch) assist in PTU longevity? I see how it could help with the clutch unit, but now sure how it relates to the PTU

Part of my questioning is, if the PTU is simple ring and pinion, and there is no clutch pak in there; I can't for the life of me understand why Royal Purple turned so black with floaties within a few miles. I flushed it with normal gear oil and all seems fine now. What the heck did Royal Purple do in there? First experience with RP and i'm not sure I can justify their products in my vehicles.

Anyhow, with the vent banjo bold tightened up, the vent filters installed on ptu and rear diff, I will just change these oils out on an annual basis. This to avert the $550 replacement Ptu, plus my hours of install time.